Many systems and applications have been developed to allow people to communicate with each other. Such systems and applications may provide communication via emails, instant messages, text messages, web/online postings, etc.
Email systems typically use servers to receive the electronic messages from the senders, to store and/or forward the messages on behalf of the senders, and to deliver the messages to the recipients. Since the servers can store the messages for a period of time before delivery, a recipient and a sender do not have to establish a direct communication connection to facilitate the transmission of the electronic message. Thus, the sender and the recipient do not have to be online simultaneously for email communications.
In an email system, an email client application is typically used to receive and display messages and to compose and send messages. The email client application communicates with one or more email servers to receive and send messages. Email addresses are used to identify the recipients of the messages.
An email client application may be a stand alone application running on a user terminal (e.g., a personal desktop or portable computer, a personal digital assistant (PDA), or a smart phone). The email client application stores messages received from one or more email servers, and can display the stored messages to a user even when the user terminal is not connected to the network.
An email client application may also be implemented in part via a server. The server stores the messages on behalf of a user, and when requested, formats a message as a web page for display on a browser used by the user.
Instant messaging (IM) allows real-time communication between people. A communication connection between the devices of the participants in an instant messaging session is required for the delivery of the instant messages sent during the session. User names are typically used to identify the online presence and thus the online addresses (e.g., Internet Protocol (IP) addresses) of the users, which are used to establish the communication connections for the instant messaging session. Therefore, the user names of instant messaging systems can be considered as the addresses for establishing online connections for instant messaging sessions, from the point of view of the users.
Text messaging allows users to communicate via mobile phones over a cellular communications network. Text messages are typically transmitted via Short Message Service (SMS) or Multimedia Messaging Service (MMS). The phone numbers of the mobile phones are used as the addresses of the recipients of the text messages.
Some user terminals (e.g., personal computers, PDA, mobile phones) may support communications in multiple modes, such as email, instant messages, and text messages.
Some applications have been developed to organize address information for users. For example, an address application may store information about a plurality of persons. For each of the persons, the address application may store the name of the person, the email address of the person, the street address of the person, the IM address of the person, the web page address of the person, phone numbers of the person, etc. A person may have several distinct email addresses used concurrently to receive email messages.
Electronic messaging systems may be abused to send unsolicited bulk messages indiscriminately. Such messages may be considered spam; and some systems and applications have been developed in an effort to identify and filter out spam messages.
However, a spam filter may falsely identify a message as spam and thus may cause the user to lose messages. Some email systems allow their users to add the email addresses of their friends in an address book associated with the corresponding email system to avoid or reduce the chances that the emails from their friends are falsely identified as spam.